1. Field of the Invention
The present invention relates, generally to a disk carrier assembly and, more specifically, to an axially fixed disk carrier assembly for a multi-disk clutch for a transmission.
2. Description of the Related Art
Conventional disk clutch assemblies include multiple annular disk shaped outer friction plates, which on their outer circumference are provided with radial outward directed teeth to be axially slidable and fixed against rotation on inwardly facing axial grooves of a drum shaped outer disk carrier. The prior art disk clutch assemblies further include multiple annular disk-shaped inner friction plates, which on their inner circumference are provided with radial inwardly directed teeth to be axially slidable and fixed against rotation in outward facing axial grooves of a cylindrical inner disk carrier. The outer and inner friction plates are arranged alternating axially and are bathed in an oil bath by the surrounding hydraulic fluid. By increasing the pressure of the hydraulic fluid the friction plates are axially pressed against each other, whereby the clutch is closed for the frictional transmission of torque between the outer disk carrier and the inner disk carrier. On the other hand, the disk clutch is opened by the reduction or removal of pressure of the hydraulic fluid.
The following discussion is based upon a conventional disk carrier assembly, wherein the disk carrier exhibits, distributed about the disk-facing circumference of a cylinder segment, alternating axial grooves and axial projections, and which on one axial end is connected with a hub via a drive plate, and wherein, for transmission of torque, a rotationally fixed connection is established between the drive plate and the disk carrier via a slide-in or plug-in gear teeth, in which radial gear teeth provided at the outer circumference of the drive plate engage in corresponding radial recesses in the disk carrier. The disk carrier could be either an outer disk carrier or an inner disk carrier, wherein the axial grooves serve respectively for receiving the disk teeth of the concerned disks or friction plates. In particular in the case of an outer disk carrier, due to the relatively large dimensions, both the disk carrier as well as the drive plate are for weight and cost reasons preferably made as sheet press and punch components.
According to the state of the art, this type of plug-in gearing between the disk carrier and drive plate is designed with axial play factored in to allow for compensation for thermal expansion of the disk carrier and for axial movements of the drive. For example, this type of conventional axial free play of the teeth of the drive plate with respect to the disk carrier is described in DE 33 21 659 A1. However, in an automotive transmission, the drive plate has the task of introducing the torque produced by the drive motor into the disk carrier of a disk clutch such that this existing axial play is disadvantageous before the clutch components heat up and expand. Due to the manner of operation of an internal combustion piston engine the produced torque is not produced evenly over all angles of rotation, but rather is a factor of the number and arrangement of the cylinders, peaking in correspondence with the expansion gas force in the individual cylinder combustion spaces. Additionally, the piston rod of the internal combustion piston motor is caused by the effective gas forces to undergo a periodic warping, which is transmitted to the input side of the transmission or, as the case may be, the preceding motor clutch, and results in a recoiling action of the drive plate. This recoil movement causes, in the case of a conventional drive plate having axial play, an axial slippage between the teeth of the drive plate and the recesses of the disk carrier. The axial slippage causes noticeable drivetrain noise and as the clutch components age, a continued frictional wearing of the affected contact surfaces, which results in excessive amounts of axial play and thus a greater undesired noise output. Therefore, there exists a need for an axially fixed disk carrier assembly that does not include axial play and yet compensates for the thermal expansion of the disk carrier assembly components.